* {
    margin: 0;
    padding: 0;
}

li {
    list-style: none;
}

.img {
    display: block;
}

a {
    text-decoration: none;
}

.ellipsis {
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}


.img {
    width: 350px;
    height: 350px;
    position: relative;
    background: url('../tools/面向对象：二倍图/imgs/1.jpg');
}

.mask {
    width: 50px;
    height: 50px;
    background-color: yellow;
    opacity: .5;
    position: absolute;
    left: 0px;
    top: 0px;
    display: none;
}

.enlarge {
    width: 100px;
    height: 100px;
    background: url('../tools/面向对象：二倍图/imgs/1.big.jpg');
    background-position: 0px 0px;
}